Does maternal diabetes delay fetal pulmonary maturity?

Concordance of the risk of neonatal respiratory morbidity assessed by quantitative ultrasound lung texture analysis in fetuses of twin pregnancies

To evaluate the concordance of the risk of neonatal respiratory morbidity (NRM) assessed by quantitative ultrasound lung texture analysis (QuantusFLM) between twin fetuses of the same pregnancy. Prospective study conducted in twin pregnancies. Fetal ultrasound lung images were obtained at 26.0–38.6 weeks of gestation. Categorical (high or low) and continuous results of the risk of NRM were compared between twins. Fetal ultrasound lung images from 131 pairs (262 images) of twins were included. The images were classified into three gestational age ranges: Group 1 (26.0–29.6 weeks, 78 images, 39 pairs [29.8%]); Group 2 (30.0–33.6 weeks, 98 images, 49 pairs [37.4%]) and Group 3 (34.0–38.6 weeks, 86 images, 43 pairs [32.8%]). Concordance was good in Groups 1 and 3 and moderate in Group 2. In Groups 2 and 3 at least one fetus presented high-risk results in 26.5% and 11.6% of twin pairs, respectively. Only gestational age < 32 weeks, gestational diabetes mellitus, and spontaneous conception were associated with a high risk of NRM in Group 2. There was good concordance of the risk of NRM between twins < 30.0 weeks and > 34.0 weeks. From 30.0 to 33.6 weeks 26.5% of the twin pairs had discordant results, with moderate concordance of the risk of NRM.

Molecular Mechanisms of Maternal Diabetes Effects on Fetal and Neonatal Surfactant

Respiratory distress is a significant contributor to newborn morbidity and mortality. An association between infants of diabetic mothers (IDMs) and respiratory distress syndrome (RDS) has been well recognized for decades. As obesity and diabetes prevalence have increased over the past several decades, more women are overweight and diabetic in the first trimester, and many more pregnant women are diagnosed with gestational diabetes. Glycemic control during pregnancy can be challenging due to the maternal need for higher caloric intake and higher insulin resistance. Surfactant is a complex molecule at the alveolar air-liquid interface that reduces surface tension. Impaired surfactant synthesis is the primary etiology of RDS. In vitro cell line studies, in vivo animal studies with diabetic rat offspring, and clinical studies suggest hyperglycemia and hyperinsulinemia can disrupt surfactant lipid and protein synthesis, causing delayed maturation in surfactant in IDMs. A better understanding of the molecular mechanisms responsible for surfactant dysfunction in IDMs may improve clinical strategies to prevent diabetes-related complications and improve neonatal outcomes.

Adverse neonatal outcomes associated with pregestational diabetes mellitus in infants born preterm

BACKGROUND

Pregestational diabetes mellitus is associated with a higher risk of adverse pregnancy outcomes. Based on the available data, it is unclear whether infants born preterm to mothers with pregestational diabetes mellitus are at a higher risk of adverse outcomes than other preterm infants.

OBJECTIVE

This study aimed to quantify the neonatal complications associated with pregestational diabetes mellitus in infants born preterm.

STUDY DESIGN

This was a retrospective cohort study of all nonanomalous singleton neonates born in Texas from 2006 to 2014. Analysis was limited to births between 24 and 36 weeks' gestation and excluded multiple births, stillbirths, fetal congenital anomalies, neonates born to mothers with gestational diabetes mellitus, and neonates born to mothers with chronic hypertension. Results were stratified by pregestational diabetes mellitus status. Neonatal outcomes of interest included infant death, neonatal intensive care unit admission, low 5-minute Apgar scores, assisted ventilation of >6 hours, surfactant administration, and seizures. Multivariate logistic regression analysis was performed to estimate the association between pregestational diabetes mellitus and neonatal outcomes controlling for potential confounding variables.

RESULTS

After predefined exclusions, 277,210 births were analyzed, 4164 of which were to mothers with pregestational diabetes mellitus. The comparison group consisted of mothers without pregestational diabetes mellitus. The preterm infant mortality rates between the pregestational diabetic and nondiabetic groups were similar. However, after adjusting for confounding variables, there was an increased risk of infant mortality for preterm neonates born to mothers with pregestational diabetes mellitus. In infants born preterm, pregestational diabetes mellitus was associated with an increased risk of infant death, low 5-minute Apgar score, prolonged assisted ventilation, surfactant requirement, and neonatal intensive care unit admission. Neonates born before 34 weeks' gestation had an increased risk of assisted ventilation of >6 hours, neonatal intensive care unit admission, and seizure. Neonates born to mothers with pregestational diabetes mellitus in the late preterm period between 34 and 36 weeks' gestation had an increased risk of low Apgar score at 5 minutes, assisted ventilation of >6 hours, surfactant use, and neonatal intensive care unit admission.

CONCLUSION

Pregestational diabetes mellitus is associated with a higher risk of adverse neonatal outcomes in infants born preterm.

The association of pregestational and gestational diabetes with severe neonatal morbidity and mortality

OBJECTIVE

To estimate the association between maternal diabetes and severe neonatal morbidity.

STUDY DESIGN

Retrospective cohort study of nonanomalous neonates born 24⁰-41⁶ weeks' gestation from two large multisite U.S. cohorts, Cesarean Registry and Consortium on Safe Labor. The exposure was pregestational versus gestational versus no diabetes. The composite neonatal outcome included respiratory distress syndrome, mechanical ventilation, necrotizing enterocolitis, grade 3-4 intraventricular hemorrhage, and death. Multivariable logistic regression estimated the association between diabetes and neonatal morbidity.

RESULT

Of 196,006 eligible neonates, 2993 (1.5%) were born to mothers with pregestational diabetes and 10,549 (5.4%) with gestational diabetes. Pregestational diabetes was associated with higher odds of neonatal morbidity versus gestational diabetes (aOR 2.27, 95% CI 1.95-2.64), as well as no diabetes (aOR 1.96, 95% CI 1.63-2.35). Gestational diabetes was associated with higher odds of neonatal morbidity versus no diabetes (aOR 1.16, 95% CI 1.04-1.30).

CONCLUSION

Pregestational and gestational diabetes are risk factors for severe neonatal morbidity.

Should antenatal corticosteroids be considered in women with gestational diabetes before planned late gestation caesarean section

Babies born to mothers with gestational diabetes mellitus (GDM) are at a greater risk of developing respiratory complications and hypoglycaemia than those born to mothers without diabetes. However, there is currently insufficient evidence as to whether these risks are altered by antenatal corticosteroids after 37 weeks gestation. This retrospective study suggests that antenatal corticosteroids probably reduce respiratory admissions to the newborn intensive care unit with a mild increase in neonatal hypoglycaemia in women with GDM who deliver via caesarean section after 37 weeks gestation. Consequently, we recommend a randomised, controlled trial is required to determine the efficacy and safety of antenatal corticosteroids specifically in women with GDM.

Consequences of a Maternal High-Fat Diet and Late Gestation Diabetes on the Developing Rat Lung

Rationale

Infants born to diabetic or obese mothers are at risk of respiratory distress and persistent pulmonary hypertension of the newborn (PPHN), conceivably through fuel-mediated pathogenic mechanisms. Prior research and preventative measures focus on controlling maternal hyperglycemia, but growing evidence suggests a role for additional circulating fuels including lipids. Little is known about the individual or additive effects of a maternal high-fat diet on fetal lung development.

Objective

The objective of this study was to determine the effects of a maternal high-fat diet, alone and alongside late-gestation diabetes, on lung alveologenesis and vasculogenesis, as well as to ascertain if consequences persist beyond the perinatal period.

Methods

A rat model was used to study lung development in offspring from control, diabetes-exposed, high-fat diet-exposed and combination-exposed pregnancies via morphometric, histologic (alveolarization and vasculogenesis) and physiologic (echocardiography, pulmonary function) analyses at birth and 3 weeks of age. Outcomes were interrogated for diet, diabetes and interaction effect using ANOVA with significance set at p≤0.05. Findings prompted additional mechanistic inquiry of key molecular pathways.

Results

Offspring exposed to maternal diabetes or high-fat diet, alone and in combination, had smaller lungs and larger hearts at birth. High-fat diet-exposed, but not diabetes-exposed offspring, had a higher perinatal death rate and echocardiographic evidence of PPHN at birth. Alveolar mean linear intercept, septal thickness, and airspace area (D₂) were not significantly different between the groups; however, markers of lung maturity were. Both diabetes-exposed and diet-exposed offspring expressed more T1α protein, a marker of type I cells. Diet-exposed newborn pups expressed less surfactant protein B and had fewer pulmonary vessels enumerated. Mechanistic inquiry revealed alterations in AKT activation, higher endothelin-1 expression, and an impaired Txnip/VEGF pathway that are important for vessel growth and migration. After 3 weeks, mortality remained highest and static lung compliance and hysteresis were lowest in combination-exposed offspring.

Conclusion

This study emphasizes the effects of a maternal high-fat diet, especially alongside late-gestation diabetes, on pulmonary vasculogenesis, demonstrates adverse consequences beyond the perinatal period and directs attention to mechanistic pathways of interest. Findings provide a foundation for additional investigation of preventative and therapeutic strategies aimed at decreasing pulmonary morbidity in at-risk infants.

Stillbirth in the pregnancy complicated by diabetes

Pregestational diabetes currently complicates 4% of pregnancies, while gestational diabetes complicates approximately 8% of pregnancies. Increased risk of stillbirth in diabetic pregnancies has been a well-known and recognized complication for decades. While stillbirth rates for diabetic pregnancies have decreased due to screening, treatment, and antenatal surveillance of these patients, about 4% of all stillbirths remain attributable to diabetes, and diabetic pregnancies continue to be at increased risk for perinatal mortality. The purpose of this article is to review the literature on the epidemiology, pathophysiology, and prevention, as well as future research, of diabetes-associated perinatal mortality.

Amniotic lamellar body counts determined with the Sysmex XE-2100 analyzer to predict fetal lung maturity during diabetic and other complicated pregnancies

OBJECTIVE

The detection of amniotic lamellar bodies (LB) has been shown to be a rapid and simple way to assess fetal lung maturity (FLM). The maturity thresholds for LB vary due to different factors, one being the type of particle-count analyser used.

MATERIAL AND METHODS

The Sysmex XE-2100 hematological analyser was evaluated in determination of amniotic LB counts and compared with lecithin/sphingomyelin (L/S) and phosphatidylglycerol (PG) determination. We analysed 132 amniotic samples from a total of 109 mothers (71 diabetic) with 112 infants. Results. The correlation between the LB counts obtained with the Sysmex XE-2100 and our reference thin layer chromatography (TLC) phospholipid method was good. Samples with low L/S ratio (< or = 2.0) and no PG (i.e. premature fetal lung status), had low LB counts (n = 18, mean 8500/L, range 1000-26000), whereas 51 samples with mature fetal lung status had high LB counts (mean 63600/uL, range 20,000-139,000). In all our four cases of respiratory distress syndrome the LB counts were low (range 1000-28000/uL). The reference values for FLM determination were established: < or = 6000/microL for immature, values between 7000 and 35,000/uL for borderline results and >35,000/uL for mature. CONCLUSIONS. The amniotic LB count analysis with Sysmex XE-2100 has many advantages being a repeatable, inexpensive and quantitative method with a very short turn-around time. Consequently, our routine is to perform LB counts initially from all amniotic samples and only borderline LB results are analysed with TLC.

Delayed lung maturation of foetus of diabetic mother rats develop with a diminish, but without changes in the proportion of type I and II pneumocytes, and decreased expression of protein D-associated surfactant factor

Newborn children of diabetic mothers have an increased morbidity and mortality because of respiratory distress syndrome. We study lung histogenesis during intrauterine development of offspring of diabetic Sprague-Dawley rats at 18, 19 and 21 days of gestation (DG). Pregnant rats were grouped into diabetic (streptozotocin-induced), citrate, and control groups; five female and five male offspring were selected randomly from each group at 18, 19 and 21 DG, and a biopsy of the lung was taken and processed in paraffin for histological examination. The biopsy for the transmission electron microscopy (TEM) analysis was taken at 21 days. A delay in alveolization of the offspring at 18, 19 and 21 days of the diabetic group was observed, which was confirmed at TEM level, and also less quantity of protein D associated to surfactant in diabetic group was detected (P < 0.001). The foetuses of the diabetic group presented a delay in lung histogenesis and in differentiation of the type II pneumocytes cells, but conserved the proportion with a decrease in 50% of pneumocytes, accompanied by a diminish of protein D associated to surfactant factor.

The role of nitric oxide on matrix metalloproteinase 2 (MMP2) and MMP9 in placenta and fetus from diabetic rats

Matrix metalloproteinases (MMPs) play an important role in tissue remodeling that accompanies the rapid growth, differentiation, and structural changes of the placenta and several fetal organs. In the present study, we investigated whether the diabetic maternal environment may alter the regulatory homeostasis exerted by nitric oxide (NO) on MMPs activity in the feto-placental unit from rats at midgestation. We found that NADPH-diaphorase activity, which reflects the distribution and activity of NO synthases (NOS), was increased in both placenta and fetuses from diabetic rats when compared with controls. In addition, while a NO donor enhanced MMP2 and MMP9 activities, a NOS inhibitor reduced these activities in the maternal side of the placenta from control rats. This regulatory effect of NO was only observed on MMP9 in the diabetic group. On the other hand, the NO donor did not modify MMP2 and MMP9 activities, while the NOS inhibitor reduced MMP9 activity in the fetal side of both control and diabetic placentas. In the fetuses, MMP2 was enhanced by the NO donor and reduced by the NO inhibitor in both fetuses from control and diabetic rats. Overall, this study demonstrates that NO is able to modulate the activation of MMPs in the feto-placental unit, and provides supportive evidence that increased NOS activity leads to NO overproduction in the feto-placental unit from diabetic rats, an alteration closely related to the observed MMPs dysregulation that may have profound implications in the formation and function of the placenta and the fetal organs.

The evolution of neonatology

In 1960, the terms "neonatology" and "neonatologist" were introduced. Thereafter, an increasing number of pediatricians devoted themselves to full-time neonatology. In 1975, the first examination of the Sub-Board of Neonatal-Perinatal Medicine of the American Board of Pediatrics and the first meeting of the Perinatal Section of the American Academy of Pediatrics were held. One of the most important factors that improved the care of the neonate was the miniaturization of blood samples needed to determine blood gases, serum electrolytes, glucose, calcium, bilirubin, and other biochemical measurements. Another factor was the ability to provide nutrition intravenously, and the third was the maintenance of normal body temperature. The management of respiratory distress syndrome improved with i.v. glucose and correction of metabolic acidosis, followed by assisted ventilation, continuous positive airway pressure, antenatal corticosteroid administration, and the introduction of exogenous surfactant. Pharmacologic manipulation of the ductus arteriosus, support of blood pressure, echocardiography, and changes in the management of persistent pulmonary hypertension, including the use of nitric oxide and extracorporeal membrane oxygenation, all have influenced the cardiopulmonary management of the neonate. Regionalization of neonatal care; changes in parent-infant interaction; and technological changes such as phototherapy, oxygen saturation monitors, and brain imaging techniques are among the important advances reviewed in this report. Most remarkable, a 1-kg infant who was born in 1960 had a mortality risk of 95% but had a 95% probability of survival by 2000. However, errors in neonatology are acknowledged, and potential directions for the future are explored.

Alterations in segmentary branch pulmonary artery blood flow velocimetry in fetuses of diabetic mothers

OBJECTIVE

To evaluate pulmonary blood flow in fetuses of diabetic mothers by measuring changes in fetal segmentary pulmonary artery blood flow velocimetry throughout pregnancy.

METHODS

Thirty-eight women with pregestational diabetes between weeks 18 and 38 were compared with 99 women with singleton low-risk gestations as controls. Flow velocity waveforms at the proximal middle and distal segments of the right pulmonary artery were obtained with power and color Doppler sonography in all fetuses. The pulsatility index of each segment was compared between the 2 groups. The mean value and 95% confidence interval for each segment were determined in correlation with gestational age for both groups.

RESULTS

The highest mean pulsatility indices were obtained in the proximal segment of the pulmonary artery and were 2.25 in the diabetes group and 2.36 in controls. The mean pulsatility indices were significantly decreased in the middle and distal segments to 1.59 and 1.10 in the diabetes group and to 1.57 and 1.02 in controls (P < .05). There were no significant differences in pulsatility indices measured at the proximal and middle segments between the study and control groups. However, the mean pulsatility index +/- SD measured at the distal segment in the diabetic group was 9% higher than in controls (1.10 +/- 0.13 versus 1.02 +/- 0.12; P = .01). The mean pulsatility index (in the study and control groups) in each arterial segment did not change significantly throughout gestation (P > .1).

CONCLUSIONS

. In human fetuses throughout gestation, the pulmonary circulation maintains stable vascular resistance in both diabetic and normal pregnancies. However, in all gestations, the pulsatility index in each segment of the pulmonary artery is unique and reflects the proximity to the heart and the impedance at each location. The significantly higher pulsatility index in the diabetes group might be related to alterations in the microcirculation of diabetic patients.

Testing for fetal lung maturation: a biochemical "window" to the developing fetus

Fetal lung maturity testing represents a major milestone in perinatology. This article critically evaluates specific controversies regarding the methodologies used to measure pulmonary surfactant in AF and how well each of these techniques performs both in principle and application. The clinical utility of fetal lung maturity testing as it applies to particularly difficult complications of pregnancy is discussed. These technical and clinical issues are framed by the scientific and empiric evidence that is used as the rationale for such testing and its implementation in the effective management of preterm delivery.

Prospective delivery of reliably dated term infants of diabetic mothers without determination of fetal lung maturity: comparison to historical control

OBJECTIVE

To determine whether omitting fetal lung maturity (FLM) testing prior to delivery in term pregnancies complicated by gestational (GDM) and pregestational diabetes mellitus would increase the risk of neonatal respiratory distress syndrome (RDS).

METHODS

In a 2-year study (1990-91), 1,457 pregnant women with accurately dated pregnancies were enrolled after 37 completed weeks and prospectively followed through delivery without FLM testing (study group). The prevalence of RDS and other neonatal outcomes was compared with a historical control group (n = 713, 1988-89) who had undergone determination of lecithin/sphingomyclin ratio prior to delivery at term. Logistic regression analysis was performed to determine independent predictors of RDS.

RESULTS

The study group compared to the control group had less severe diabetes: diet-controlled GDM, 35% vs. 18%, respectively; insulin-requiring GDM, 42% vs. 42%, respectively; undiagnosed type-2 diabetes, 14% vs. 31%, respectively; and pre-existing diabetes, 9.6% vs. 8.8%, respectively, p < 0.001. RDS rates in the study group (0.8%) and control group (1.0%) were not significantly different, nor were rates of resuscitation at delivery, neonatal intensive care admission or hospitalization days. Logistic regression analysis found only Cesarean delivery to be independently predictive (adjusted OR 2.21, 95% CI 2.04-2.27) of RDS. Non-predictive variables included FLM testing, diabetic classification, insulin use, poor third-trimester glycemic control, chronic hypertension, pre-eclampsia, labor, neonatal gender, gestational age or large-for-gestational-age fetuses.

CONCLUSIONS

Routine FLM testing did not change the RDS prevalence in reliably dated, term infants of diabetic mothers and should be abandoned. Delivery by Cesarean section was associated with increased RDS.

The controversy surrounding fetal lung maturity in diabetes in pregnancy: a re-evaluation

It is beyond the scope of this article to discuss the biochemical markers of fetal lung maturity and their pathophysiological characteristics. This information can be found in several textbooks and review articles. Instead, this article addresses controversial issues that confront the obstetrician in daily clinical practice related to the role of diabetes (glucose) as the teratogen for lung morbidity, and the association between lung maturity testing results and actual lung morbidity.

Lung maturation in diabetes in pregnancy: if and when to test

Poorly controlled maternal diabetes in pregnancy may delay fetal pulmonary maturation. However, diabetic women with good glycemic control have fetal lung maturation at the same gestational age as nondiabetic women. With modern ultrasound technology, gestational dates can be accurately assessed in the first or early second trimester. Respiratory distress syndrome is rare in nondiabetic and well-controlled diabetic pregnancies confirmed by early ultrasound to be at or beyond 37 weeks. Early confirmation of dates thus eliminates the need for amniotic fluid assessment of fetal lung maturity prior to elective delivery at or beyond 38 weeks in well-controlled diabetic and nondiabetic women. Poorly controlled diabetic women and pregnancies without early ultrasound verified dates may require amniotic fluid analysis for lung maturity prior to elective delivery.

A spectrum of glucose thresholds may effectively prevent complications in the pregnant diabetic patient

This article outlines the probable positive relationship between levels of maternal glycemia and perinatal morbidity and mortality. A spectrum of different glucose thresholds can be established and used appropriately to prevent each complication. This article also outlines the concept of normality and what definitions of normality should be used to evaluate the relationship between the level of glycemia and perinatal outcome. Definitive conclusions are hampered by a lack of uniformity in definitions and interventions, and by a failure in some analyses to control for confounding variables. However, it is suggested that different levels of glycemia are required to prevent different diabetic complications. Thus, although it is not always possible to achieve targeted levels of glycemic control in all patients, any improvement will be beneficial because it will affect fetal complications associated with that glucose threshold.

A comparison of amniotic fluid fetal pulmonary phospholipids in normal and diabetic pregnancy

OBJECTIVE

Our purpose was to determine whether there are differences in the timing of the appearance of various amniotic fluid fetal pulmonary phospholipids in normal and diabetic pregnancy.

STUDY DESIGN

A case-control study of 295 subjects with diabetes and 590 control subjects was performed by use of gestational age-matched amniocentesis specimens analyzed for lecithin/sphingomyelin (L/S) ratio, phosphatidylinositol (PI), and phosphatidylglycerol (PG) composition. Diabetic subjects were stratified according to type of diabetes, degree of blood glucose control, and birth percentile of the neonate.

RESULTS

There was no difference in L/S ratios over gestational age by type of diabetes or quality of glycemic control. Women with preexisting diabetes had significantly higher PI levels at 33 to 35 weeks' gestation, which became similar to levels of control subjects after 36 weeks, whereas patients with gestational diabetes mellitus and control subjects had similar PI levels throughout. In diabetic subjects, the onset of production of PG was delayed from 35.9 +/- 1.1 weeks (controls) to 38.7 +/- 0.9 weeks (overt diabetics) and 37.3 +/- 1.0 weeks for gestational diabetes mellitus (P <.001). The delay in PG synthesis was not related to infant sex, level of maternal glucose control, or fetal macrosomia.

CONCLUSIONS

Fetal pulmonary maturation, as evidenced by the onset of PG production in the amniotic fluid, is delayed in diabetic pregnancy by 1 to 1.5 weeks. This delay appears to be associated with an early and sustained elevation in amniotic fluid PI levels at 32 to 34 weeks.

Comparison of disaturated phosphatidylcholine and fetal lung maturity surfactant/albumin ratio in diabetic and nondiabetic pregnancies

We studied fetal lung maturity (FLM) by the amniotic fluid surfactant/albumin (FLM S/A) ratio and the disaturated phosphatidylcholine (DSPC) amniotic fluid levels at different gestational ages in diabetic (179 women with type 1 diabetes mellitus antedating pregnancy; infants delivered within 72 hours after amniotic fluid testing for DSPC level and FLM S/A ratio) and nondiabetic pregnancies (2 independent nondiabetic groups, 300 for FLM S/A ratio and 1,231 for DSPC level). The degree of maternal glycemia during gestation was estimated by serial measurements of hemoglobin A1. Multiple regression analyses, including gestational age (GAs) and diabetic status as independent variables and FLM S/A ratio and DSPC level as dependent variables, revealed significant effect from diabetic status and GA for FLM S/A ratio and a significant effect from GA but not from diabetic status for DSPC level. Glucose levels were controlled adequately throughout gestation as reflected by mean total glycated hemoglobin levels. Amniotic fluid levels of DSPC, the major surface tension-lowering component of pulmonary surfactant, are not significantly different between diabetic and nondiabetic pregnancies at different GAs.

Level of glycemia and perinatal outcome in pregestational diabetes

This article provides the reader with relevant information regarding the association between level of glycemia and perinatal outcome in preexisting diabetes. Although the glycemic profile is a continuum in nature, different thresholds of glucose are associated with fetal complications such as stillbirth, spontaneous abortion, congenital anomalies, fetal macrosomia, and metabolic and respiratory complications. For each complication, a different targeted threshold of normality is required. Thus, although it is not always possible to achieve optimal glycemic control in all patients, any improvement will be beneficial because it will reduce the rate of complications for a given glucose threshold.

Fetal lung maturity in pregnancies complicated by insulin-dependent and gestational diabetes: a matched cohort study

OBJECTIVE

To study fetal lung maturity (FLM) as determined by amniotic fluid (AF) tests in diabetic pregnancies (DP) under euglycemic metabolic control, in comparison with matched controls (C).

PATIENTS AND METHODS

From 514 consecutive pregnancies where amniocentesis was performed for FLM assessment, we selected 45 glycemic controlled DP. Nineteen DP were Type I (IDDM) and 26 pregnancies were diagnosed Type III (GDM). Cases were matched to C by therapy with corticosteroids, gestational age at amniocentesis, pregnancy complications other than diabetes and gender. FLM was determined by the shake test and lamellar bodies (LB) count, lecithin/sphingomyelin (L/S) ratio (planimetric and stechiometric) and phosphatidylglycerol presence (PG). DP were further sub-divided according to gestational age period at amniocentesis, type of diabetes, associated therapy and fetal malformations.

RESULTS

RDS (n=2) and neonatal wet lung (n=5) were diagnosed in neonates from diabetic mothers. We found no statistical difference when comparing FLM indices between DP and C groups: shake test 3.1:1+/-1.2 vs. 2.7:1+/-1.2, P<0.40; planimetric L/S 3.4+/-1.4 vs. 3.1+/-2.0, P<0.27; stechiometric L/S 8.2+/-7.4 vs. 7.1+/-6.1, P<0.54; percentage of PG positivity 57% vs. 46%, P<0.13; lamellar bodies count (X10(3)/microl) 42.8+/-36.9 vs. 41.5+/-30.4, P<0.72. No differences were found between DP and controls for subgroups according to gestational age, type of Diabetes (IDDM or GDM), congenital lesions and associated therapy.

CONCLUSIONS

In euglycemic, metabolically controlled diabetic patients FLM is not delayed, however an increased risk for neonatal wet lung should be considered.

Surfactant secretion by type II pneumocytes is inhibited by high glucose concentrations

Delayed fetal lung maturation is observed in poorly controlled diabetic pregnancies. To investigate whether elevated glucose levels inhibit basal surfactant secretion and synthesis in type II cells and whether inhibitory effects on secretion can be reversed by secretagogues, type II cells isolated from 20-day fetal rat lung explants were initially cultured in [H3] choline containing media with glucose concentrations of 5.5, 10, 25, 50, and 100 mM, or in equiosmolar mannitol controls. Further incubation in nonradioactive media containing matched glucose levels with and without 1 x 10(-5) M terbutaline 1 x 10(-6) M and 1 x 10(-8) M 12-O-tetradecanoylphorbol 13-acetate (TPA) allowed assessment of incorporation of choline into phosphatidylcholine (PC) and its subsequent secretion. PC secretion was inhibited by culture in high glucose conditions, resulting in an approximately 30% reduction in secretion under 50 and 100 mM glucose conditions compared to culture at 5.5 or 10 mM glucose (p < .01); this decrease could not be explained by changes in osmolarity or in all viability after culture in high glucose. Insulin (1 unit/mL) had no significant impact on secretion (92 +/- 7% of control). Terbutaline-stimulated cells grown under 50 and 100 mM glucose conditions had significantly lower secretion rates than did terbutaline-stimulated cells cultured in 5.3 mM glucose (p < .05). Exposure to TPA resulted in significant increase in surfactant secretion by cells grown in both 5.5 and 100 mM glucose; however, the percentage increase (39.5 +/- 6.8% and 94.8 +/- 8.0% with 10(-8) M and 10(-6) MTPA, respectively) was significantly lower than in controls (87.8 +/- 8.0% and 152.1 +/- 18.8%, respectively) (p < .001). Choline incorporation into PG was also decreased by 100 mM glucose to 77 +/- 9% of control (p < .01). These data indicate that high glucose levels inhibit both surfactant synthesis and baseline and secretagogue-stimulated surfactant secretion by type II cells. This inhibitory effect on surfactant secretion may further exacerbate the decrease in surfactant synthesis and the pulmonary maturational delay seen in infants of diabetic pregnancies.

Standards of laboratory practice: evaluation of fetal lung maturity

In this standard of laboratory practice I recommend guidelines for fetal lung maturity (FLM) testing. If possible, obtain a 10-mL uncontaminated sample by amniocentesis. Keep the amniotic fluid at 4 °C and mix well before testing. If centrifugation is required, strictly adhere to the protocol. Most laboratories should offer a rapid test, such as fluorescence polarization, phosphatidylglycerol, or foam stability index, daily on both a routine and emergency basis. Requests for lecithin/sphingomyelin ratio may be referred to a reference laboratory. Communicate immediately the results of any FLM test to the ordering location. The report should contain the result, sample contamination, and reference information. Separate reference intervals for diabetic patients are not recommended.

Management of gestational diabetes mellitus

This article addresses management of gestational diabetes in a two part fashion. It discusses the pathophysiology and pathogenesis of diabetes and outlines the contemporary management approach for gestational diabetes in the 1990s.

Influence of metabolic control of pregnant diabetics on fetal lung maturity

We studied the relationship between the metabolic control of pregnant diabetics and fetal lung maturity. In 31 diabetic and 20 normal pregnancies we analysed phospholipids in amniotic fluid and glycaemic control parameters. There were no differences in amniotic fluid lecithin/sphingomyelin (L/S) and phosphatidylinositol/sphingomyelin (PI/S) ratios between pregnant diabetics with strict metabolic control and the control group. Pregnant diabetics with poor metabolic control had significantly different L/S and PI/S ratios than the normal pregnant women. Six women in this group of poorly controlled diabetics had mature surfactant in amniotic fluid (L/S > or = 2.7 and presence of phosphatidylglycerol) at 32-34 weeks of amenorrhea; the difference was significant (p < 0.05) with respect to the control group. These six women had recurrent hypoglycaemic episodes (6.4 +/- 1.3 episodes/week) at 14-27 weeks of amenorrhea. Our findings suggest that hypoglycaemic stress on the fetus could disturb fetal synthesis of pulmonary phospholipids.